Many databases are growing in size such that information (or data or records) that used to be all in one table may now be split into more than one table. Applications that may use this data may sometimes be written to join the data together using a command (e.g., an SQL command).
The SQL commands UNION (“union”) and UNION ALL (“union all”) may be used by applications using data to join data from multiple tables together. With the union command, only distinct data from the multiple tables may be joined. Inherent with the union command may be a filtering operation to filter out duplicate data in order to return only distinct data. With the union all command, all data from the multiple tables may be joined (e.g., the data from the multiple tables are joined without filtering).